I. Technical Field
The present invention relates to a component-mounted board production apparatus for mounting electronic components onto a board on which solder is placed on its board-side electrodes, as well as to a position control method for electronic components in the component-mounted board production apparatus.
II. Description of the Related Art
For mounting of electronic components onto a board such as a printed circuit board having electrodes formed on its top surface, a widely practiced method is that with solder paste preliminarily printed on the board-side electrodes and with component-side electrodes placed on the solder paste pieces, solder reflowing is performed so that the component-side electrodes will get wet with the molten solder to fulfill the bonding. The board-side electrodes and the component-side electrodes need to be accurately bonded to each other, respectively, with a view to ensuring the mounting quality. However, there are some cases where the solder paste printed on the board-side electrodes is offset in a print position with respect to the board-side electrodes or lack in printing uniformity. In such a case, when an electronic component is placed by referencing a design-base mounting reference position so that the both-side electrodes accurately overlap with each other, such failures can occur as a phenomenon that the electronic component is offset from an original placement position, i.e. the mounting reference position, due to surface tension by the reflowing molten solder, or that the electronic component is erected by strong surface tension acting partly thereon.
As a solution to such failures, there has been proposed an electronic component mounting apparatus which is so designed that a center of area (the center of area is a center of a planar surface) is determined from planar shapes of solder paste pieces printed on a pair of board-side electrodes and then an electronic component is placed by referencing the center of area (see Japanese unexamined patent publication No. 2002-84097). By placing an electronic component by referencing the center of area of solder paste pieces printed on a pair of board-side electrodes as shown above, it becomes possible that while the reflowing molten solder is wetted and spread on the surfaces of the board-side electrodes, component-side electrodes formed at both ends of the electronic component are moved to central portions of the individual board-side electrodes, respectively, by a self alignment effect exerted by the molten solder, thereby being automatically position-corrected roughly to the design-base mounting reference position.